Fortaleza de São João, Military fort in Urca, Rio de Janeiro, Brazil

The Fortaleza de São João is a walled military compound on the western side of Guanabara Bay in Urca, Rio de Janeiro. Pale yellow and white buildings with terracotta tile roofs stand on a slope within white perimeter walls. At the lower edge, a long rectangular building with a red tile roof has a central entrance block inscribed "COP" and "EsEFEx". Behind it, two-storey buildings enclose a courtyard, and a long white-roofed range with a columned lower level runs along the left side.

Portuguese settlers founded this fortification in 1565 to defend the newly established city against French attacks. It played a central role in protecting the bay throughout various military conflicts that followed.

The fort displays Portuguese military architecture from colonial times and is viewed today as a symbol of Rio's early defense heritage. You can see how the building served different purposes over centuries while maintaining its original structure.

The fort is best visited during daylight hours when light illuminates the stone structures and the bay. You should wear sturdy shoes since the pathways are uneven and there are stairs to explore different levels.

The fort's four batteries—São José, São Martinho, São Teodósio and São Diogo—were only fully in service from 24 June 1618, when São Diogo was completed. Emperor Pedro II ordered a complete renovation in 1872, equipping it with fifteen Whitworth cannons. The army's physical training school, created in 1922, moved here in 1930.